Generally, a laser beam has two important characteristics, i.e., spatial and wavelength coherency. Spatial coherency is a phenomenon of a laser beam traveling in a straight line without scattering, which results in gathering of laser beam while traveling far distance to the final target point with its size still similarly intact as compared to that of the laser beam originating from the light source. Wavelength coherency is a characteristic of constant wavelength of a laser beam so emitted.
The objectives of using laser devices in the field of medicine are based on a variety of academical and technical theories. Devices are widely used in various fields, such as incision of skin during surgery, coagulation of hemorrhage sites, tissue welding during anastomosis of tissues such as nerves and blood vessels, tissue vaporization, photodynamic diagnosis and treatment, resurfacing, revasculariziation, hair removal, and removal of artificial pigments. Also, a laser of certain wavelength is known to facilitate certain types of post-operation treatments.
Medical laser treatment devices have many advantages (infra) over electric cauteries or electric scalpels which have been used in surgeries and other treatments.
First, a laser beam, as its name suggests, is a light beam, not electricity. When a bodily stimulation is transmitted through nerves, it is transmitted as a minute electrical signal. Even if there were nerves present at the vicinity tissues adjacent to the target tissue under surgery, the laser unlike the electric scalpel does not affect the signal transmission of the nerves at all, and therefore its use therein results in prevention of unexpected nerve damage.
Second, there are many advantages of bloodless surgery. Upon irradiation of a laser beam thereto, the tissue incision along with small blood vessels are sealed. As such, by operating with laser scalpels, surgeries can be performed almost without hemorrhaging in cases of surgeries of organs with anticipation of much hemorrhaging, such as surgeries of patients with hemorrhage tendencies, or surgeries of organs with blood vessels, such as livers or kidneys. In this manner, the underlying conditions requiring blood transfusion to a patient vanishes, and in the end, bloodless surgery has the effect of preventing diseases, which can be disseminated by way of blood transfusion, such as hepatitis.
Third, small lymphatic vessels in tissues are sealed by means of irradiation of laser beams. As such, it sharply reduces the occurrence of edema caused by accumulation of lymph after surgery and also prevents spreading of cancerous cells during surgery or thereafter.
Fourth, as compared to surgeries using conventional surgical instruments, the surgeries using laser beams result in smaller post-surgery scars on patients. As such, the occurrence of one of the causes of re-surgery, a post-surgery stricture, can be effectively reduced.
Fifth, when surgery is performed by using a laser beam, it can effectively reduce post-surgery pain by sealing the nerve ends cut at the target site.
Sixth, the use of a laser beam leads to rapid recovery of a patient by facilitating the wound healing process after surgery.
Seventh, by using a laser, with the irradiation of the laser beam, it sharply reduces hemorrhaging by way of its hemostatic action. By reducing the time required for hemostatis to this extent, it effectively reduces the operation time therein.
Eighth, since the laser beam basically uses heat, the germs are destroyed at the treatment site even if there were a bit of infection at the treatment site. As such, it sharply decreases the occurrence of post-surgery infection.
Ninth, in the past, due to general anesthesia, patients had to be hospitalized for surgeries. However, by using a laser, which enables surgeries with local anesthesia, it has the effect of saving patient's time and treatment cost.
With all these advantages, however, the laser treatment devices are problematically large in volume and also expensive. Nonetheless, with the development of laser treatment devices of reduced volume, which use semiconductor laser diodes, their usage in medicine are gradually increasing.
However, a laser beam still has the characteristic of coherency. In other words, it has the characteristic of emitting a large amount of energy with no loss while traveling in a straight line without diffusion of laser beam of a given wavelength. Accordingly, if it is a laser beam, which has enough energy to incise a tissue, it can cause substantial damage upon reaching an undesirable site, which is outside the focus, due to some errors in the laser beam. In other words, since a portion of laser beam can be reflected, and the surface of the body, not within the objective under treatment, can be wrongfully irradiated on, which can cause substantial damage if irradiated onto the body with almost no loss of its harmful energy. Due to this type harm, due caution is required while operating a medical surgery laser. For this purpose, the operation switch is duplicated in installation to prevent careless manipulation. Nonetheless, such precautious measures are insufficient in view of the capacity of the operators and the fact the object of harm is after all a human body.
Further, the semiconductor laser diode, which corresponds to a laser oscillator device, gives off too much heat due to its operational conditions. As such, it needs some means of cooling In the past, devices using water-cooling or air-cooling means were used. If theses types of water-cooling or air-cooling devices were installed thereto, there would be a limitation against reducing the overall size of a laser treatment device. Consequently, there were thorny problems with respect to difficulties in usage and handling due to its general increase in weight.